There are many different manufactures of them. Some people build their own. Some people start with a old Travel Trailer and modify it. They are getting quite common and yes I have seen them at the campground in the summer.
Personally, I am too afraid of falling though the ice to go out on it. I used to drive on lakes in my youth though. Young people do a lot of dumb things. Sure was a lot of fun spinning around on the lake in a car though.
Oh, and if your vehicle goes through, and assuming you survive, your insurance will not pay for it. Or, for getting it out of the lake and that is darned expensive.